I can't say I remember any crowds in my dreams, but I expect I have had some. I can remember one dream with at least 12 people chasing me (one of said 'crowd' was some Caesar impressionist, let's not go into that), that's as many I can remember. I expect it's very possible to have more though. It's not like you have to make up a personality for each person. In a dream, all a crowd needs to do to exist is be known as "there", if you get what I mean.